The present invention relates to digital data processing and more particularly to a method and apparatus for use in automatically searching for a string of ordered characters appearing in a data stream such as from a magnetic tape on a transmission line, etc.
In digital data processing operations it is oftentimes desirable to locate a string of ordered characters stored in some record medium or available from a data source for various purposes such as editing, channeling, processing, etc. Generally this involves providing an ordered string of reference characters which identify the string to be located. The problem of comparing ordered character strings is made more difficult when the strings are of variable length. Various schemes have attempted to deal with this problem. One approach involves the use of binary counters to account for the number of characters to be compared and the number which have been compared. The use of such counters involves several disadvantages, such as additional costs, the inefficient utilization of space and a reduction in reliability.
According, it is one object of this invention to provide an improved arrangement for automatically searching for a string of ordered characters available from a source.
A further object of this invention is to reduce the cost and complexity of circuitry involved in automatically searching for a string of ordered characters of selectable length available from a data source.
A further object of this invention is to utilize the dynamic register, which is otherwise required to buffer the tape recorder or data stream with the readout device, terminal or processor, for storing the string of candidate characters to be searched and a static/dynamic register to store and maneuver a string of reference characters in relation to the candidate character string in the dynamic buffer.
A further object of this invention is to provide improved monitoring status and input/output control of the dynamic register and the static/dynamic register employed in comparing the strings of characters stored in both registers.
Another object of this invention is to provide an improved digital data processing arrangement.
Another object of this invention is to provide an improved control arrangement for automatically searching for a string of ordered characters of selectable length available from a source with a minimum amount of circuitry and improved reliability.